BUG #3598: Strange behaviour of character columns in select with views

The following bug has been logged online:

Bug reference:      3598
Logged by:          Luiz K. Matsumura
Email address:      luiz@planit.com.br
PostgreSQL version: 8.2.4
Operating system:   Fedora Core 3
Description:        Strange behaviour of character columns in select with
views
Details:

Scenario:

CREATE TABLE table1
(
 id serial NOT NULL,
 col1 character varying(30),
 CONSTRAINT pk_table1 PRIMARY KEY (id)
);

CREATE TABLE table2
(
 fk_table1 integer,
 type1 character(3),
 id serial NOT NULL,
 CONSTRAINT pk_table2 PRIMARY KEY (id)
);

CREATE TABLE table3
(
 id serial NOT NULL,
 type2 integer,
 fk_table1 integer,
 CONSTRAINT pk_table3 PRIMARY KEY (id)
);

CREATE VIEW view1 AS
SELECT table1.id,
      table1.col1,
      table2.type1,
      NULL AS type2
FROM   table1
JOIN   table2 ON table2.fk_table1 = table1.id
UNION ALL
SELECT table1.id,
      table1.col1,
      NULL::character(3) AS type1,
      table3.type2
FROM   table1
JOIN   table3 ON table3.fk_table1 = table1.id;

When we do:

SELECT * from view1;
OR
SELECT id,col1,type1,type2 FROM view1;

column type1 return as bpchar


But if we do:
SELECT type1 FROM view1;
or
SELECT id,col1,type2,type1 FROM view1;

Now, type1 return as character(3) as expected.